Method of deflocculating bacteria



June 7, 1949. GREEN METHOD OF DEFLOCCULATING BAGTERIA Filed Sept. 28,1945 Patented June 7, 1949 UNITED METHOD F DEFLOCCULATING BACTERIA GlennGreen, Lakeville, Ohio, assignor to Syntron Company, Homer City, Pa., acorporation of Delaware Application september 2s, 1945, serial Ne.619,233 s claims. (ci. 19a-75) This invention relates to a method oftreating microscopic organisms, such as bacteria, yeasts, molds and thelike, that is particularly applicable to bacterial analysis of water,milk and the like. Many types of microscopic organisms have clumping orgrouping characteristics of growth which are so pronounced in someinstances as to be distinguishable on that account. Each such livingclump or group of microorganisms when planted or innoculated into agrowth media, such as nutrient agar, will produce only one visiblecolony regardless of the number of individuals which comprise the group.A bacterial analysis, therefore, based on clumps or groups is notaccurate because of the possible variation in size of the clumps. Priormethods of bacterial analysis, for example, the standard method of wateranalysis, involves vigorous shaking of the sample in an effort todisintegrate these clumps, and it is usual to allow for a ten percenterror in the analysis.

According to the present invention, I subject I microscopic organismswhich may be suspended or dispersed in a suitable medium, to highfrequency vibration to disintegrate or break up the clumps. Preferablythe vibration rate and amplitude are such as not to appreciably destroythe bacteria, where it is desired to promote growth of the bacteria.However, the breaking up of clumps of bacteria may be employed inconjunction with any suitable method of destroying bacteria, in whichcase precautions against the destruction of some of the bacteria byvibration need not be taken. The breaking up of the clumps of bacteriaby vibration may be employed in the preparation of vaccines and in thecultivation of bacteria for -various industrial processes, as well as inthe examination of Water, milk or other substances. l

In applying my invention to the analysis of water, I subject watersamples to vibration at 3600 to '7200 per minute at an amplitude ofabout 1/32 inch for about iive minutes. If desired, I may add anadjutant such as a sodium hexametaphosphate in the water sample tofacilitate the breaking up of clumps. The cultures then are incubated inany suitable media, such as nutrient agar, for any suitable conditionsas to'temperature, time, etc.

In the accompanying drawing, forming part of this application, wherein Ihave shown a preferred form of apparatus for carrying out my method,Figure 1 is a side view partly in section and Figure 2 is an end viewpartly in section.

Referring to the drawing, there is shown a casing I suitably securedwithin a cabinet 2. At the top of the casing I are four vibratorymembers II disposed diagonally across the four corners, each comprisingan inverted channel-shaped metal strip I2 with a hole therethrough (notshown) by which thestrip may be bolted or otherwise secured to a topplate I3, and rubber pads I4 have one voi? their respective facessecured to each side of the channel strip I2 by vulcanization, or in anyother suitable manner. The pads I4 are right and left hand, and thefaces thereof are substantially parallel. Angle strips I6 `arevulcanized to the opposite faces of pads I4 and bolts Il passtherethrough into a flange (not shown) at the top of casing I to securethe vibratory members II thereto. Table I3 nay be or' metal, wood orother suitable materia.

The unit for vibrating the table I3 comprises a vibratory motorindicated generally by the numeral 2I and in the preferred embodimentconsists of a base 22 of cast steel or other suitable material having alaminated electromagnet 23 secured therein by rivets or in any othersuitable manner. The base has holes 24 bored through the ends by whichit may be secured tothe table I3. The electromagnet 23,1 whichpreferably is in the form of a T, is surrounded by a coil or winding 25which may rest on a cushioning pad 26 of rubber or other suitablematerial, anda suitable clip 21 holds the coil in place.

The armature '28 is of laminated construction and is substantially inthe shape of a C. The laminated plates of the armature are enclosed inthicker side plates 3l oneither side, which extend partway along thelegs of the C and beyond the armature proper, all the plates being heldin assembled position by rivets or in any other suitable manner. Crossbars 29 having suitable bolt holes therein, are positioned between theside plates 3I and are welded or otherwise se' cured thereto. Adjacenteach end of the base are two vibratory members similar to members I Iwhich are indicated generally by the numerals 32 and 33 and the armatureis secured to these vibrator members by bolts 36 passing through theholes in bars 29, and nuts 3l and 38 and spacing washers 39 in between.The spacing washe r s are interposed between `horizontal bars 29 of thearmature and the top channel member 40 of the vibratory membersA(corresponding to chan- `nel members I2).

There is thus provided a proper air gap between the armature and theelectromagnet in assembled position, and the bolts 36 preferably areadjusted so that their heads 42 are not in contact with the base 22. Byreason of the non-magnetic properties of the armature supports 32 and 33the possibility of the electromagnetic flux being shunted around the airgap into the armature is eliminated. Ordinarily, when the armature isvibrating the amplitude of vibration is such that the heads 42 do notstrike the base 22. However, striking surfaces 43 of Stelllte or othersuitable hard material may be positioned on the base 22 to preventdamage in case accidental impact occurs.

In a compartment or case 45 which preferably is secured to the cabinethousing the apparatus, there is located a rheostat 41 controlled by aknob 48 extending outside of the cabinet. The cabinet also includes asnap switch 49 of the usual type. The table I3 has posts 5I and 52 atits ends which are firmly bolted to the table by nuts 53 on the ends ofthe posts, and a cross bar 54 joins the two posts. This bar preferablyis made up of an inverted channel 55 and a steel plate 56 welded acrossthe open face of the channel to provide a rigid structure. Nuts 51 and5B on the ends of posts 5I and 52 adjustably secure the cross bar 54 inposition. Recesses 5I are provided in the table and have pads 82 of corkor similar yieldable material on their bottoms to receive the samplejars or bottles 63. These bottles, which may have ground glass stoppers54, are held firmly in position by hand screws 55 threaded into bar 54and having rubber or similar resilient pads 68 secured to a plate 61which is in turn connected to screw 65 by a ball and socket joint 68.

The following specific example will illustrate the carrying out of mymethod and the operation of the apparatus. Two samples of raw water, bywhich term I mean water in its condition when it enters the waterpurification plant, are prepared for microscopic examination or platingOne sample is first placed in a bottle 63 which is then placed in arecess 52 of the table I3, the stopper 64 applied, and the hand screw 65turned down until the stopper is held firmly in place. The table andbottle then is set into vibration by supplying electric current to thevibrator, preferably from a 60 cycle source, through the switch 49 andrheostat 41 to the coil 25 to vibrate the table vertically at the rateof 7200 vibrations per minute. The vibration is carried out for fiveminutes and then both samples are incubated side by side in the sameincubator for twenty-four hours. .The following table represents theresults of a typical series of tests made on raw water, the numbersrepresenting the bacterial count.

Slffgl vibrante sample 180 130 390 62 240 210 360 180 340 105 170 110 lm90 im 100 120 1l5 180 275 340 112 280 Average 141 Average 237 Percentincrease 68 3600 per minute. The apparatus illustrated is ofparticularvalue where a number of samples are to be vibrated together. I prefer,therefore, to place the sample bottle on a resilient pad 62 of cork,rubber or the like, and hold the sample bottle in place by a resilientpressure applied to the stopper through a pad 66 of rubber or the like,the universal joint 68 allowing the pad to adapt itself to the stopperas required. The base 22 carrying the electromagnet 23 is firmly securedto the table I3 which rests upon the vibratory members li on the base l.The defluocculation of the bacteria may be assisted by the addition ofsodium hexametaphosphate, and I prefer to use about one to fifteen partsper million for this purpose, although I do not intend to be limited tothese exact proportions.

Various modifications may be made in my invention without departing fromthe spirit or scope thereof.

I claim:

l. The method of defiocculating bacteria for counting which comprisessubjecting bacteria suspended or dispersed in a medium to a verticalmechanical vibration of relatively low magnitude and a frequency of 3600to 7200 vibrations per minute.

2. The method of deiiocculating bacteria for counting which comprisessubjecting the suspended bacterial to a fixed vertical uniformmechanical vibration of relatively low magnitude and at a frequency of7200 vibrations per minute.

3. The method of deocculating bacteria for counting which comprisessubjecting the suspended bacteria to a uniform vertical mechanicalvibration of frequency of 7200 vibrations per minute at an amplitude ofabout 1/32 inch for about five minutes.

4. The method of defiocculating bacteria for counting which consists insubjecting a sample of a liquid containing the bacteria to a fixedvertical uniform mechanical vibration having a frequency of 3600vibrations per minute and varying the amplitude of the vibrations toprovide different degrees of deiiocculation.

5. The method of deflocculating bacteria for counting which consists insubjecting a sample of the liquid containing the bacteria to a fixedvertical uniform mechanical vibration having a frequency of 3600vibrations per minute and having a low magnitude for a predeterminedperiod of time, checking the bacteria count of the specimen, reapplyingthe vibrations to the specimen at an increased magnitude for apredetermined period of time, and again checking the bacteria count ofthe specimen.

GLENN GREEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,863,222 Hoermann June 14, 19322,230,997 Chambers et al. Feb. 11, 1941 2,138,839 Chambers Feb. 11, 1941OTHER REFERENCES Standard Methods for the Examination of Dairy Products,8 edition, 1941, pages 26, 136.

Philosophical Magazine & Jr. of Science Vol. 4, No. 22, Sept. 1927,pages 434, 435.

